Be careful aerating aged red wine (stored over 20 years)!! Often, these aged red wines are so volatile that aeration will cause the aromas to disappear within minutes -- thus losing the best of the wines.
You should definitely decant aged wine. But you can do that without exposing it to air. There are decanters specially designed for vintage wines.
FYI, aerating and decanting serve different purposes. For their definition, see http://www.bettertastingiwne.com/taste.
With modern 2-in-1 aerating-decanting funnel, it is commonly use to replace each other.